Gaskets for plate heat exchangers

ABSTRACT

A convention heat exchanger plate has two ports which are isolated from the heat transfer area by gaskets and an isolating bridge zone between these ports and the heat transfer zone is normally vented to atmosphere by a gap in the gasket defining it. According to the present invention the gasket is formed of harder material in the region of such vent gap to prevent the gasket material extending into the vent gap under heat and pressure.

D United States Patent 1 1 [111 3,908,757

Wright 1 1 Sept. 30, 1975 [541 GASKETS FOR PLATE HEAT 2.217.567 10/1940 Seligman et a1. 165/167 EXCHANGERS 2939.686 6/1960 Wildermuth 165/167 [75] Inventor: Felix William Wright, 111'. Crawley FOREIGN PATENTS OR APPLICATIONS England 282.343 4/1966 Australia 428.634 5 1935 U 'td K' d 165 167 [73] Assignee: The A.P.V. Company Limited, m k m}: Om

Crdwlcy England Primary E\'amim'r-Char1es J. Myhre [22] Filed; Aug, 8, 1974 Assistant Examiner-Theophil W. Streule, Jr. pp Noi: 5,5 3 Attorney, Agent. or FirmChristel & Bean [57] ABSTRACT [30] Foreign Application Priority Data A convention heat exchanger plate has two ports Aug 16, 1973 United Kingdom 38786/73 which are isolated from the heat transfer area by gaskets and an isolating bridge zone between these ports 2] U.S. Cl. 165/167 and the hea transfer zone is normally vented to atmo- 1] Int. Cl.'- F28F 3/08 sphere by a gap in the gasket defining it. According to 5 Field of Search 165/167 the present invention the gasket is formed of harder material in the region of such vent gap to prevent the [56] References Cited gasket material extending into the vent gap under heat UNITED STATES PATENTS and Pressure 2,039.216 4/1936 Feldmeier 165/167 9 Claims, 4 Drawing Figures GASKETS FOR PLATE HEAT EXCHANGERS This invention relates to plate heat exchangers.

A conventional type of plate heat exchanger comprises a separable pack of heat transfer plates to closely spaced faceto-face relationship to form flow space zones for heat transfer media between adjacent plates. The plates are formed with aligned apertures forming supply and discharge ports for the two heat exchanger media, and peripheral gaskets are provided to limit the flow space zones peripherally of the plates and to control communication between the ports and the flow space zones.

Any one flow space will thus have communication with the supply and discharge ports for one heat exchange medium, and the apertures which form part of the ports for the other medium will be surrounded by gasket portions. These separate gasket portions may be integral with, or separate from, the peripheral gaskets, as described for instance in United Kingdom Pat. Specification No. 524,909. Also, the peripheral gasket of the flow space will normally serve to isolate the flow space from a zone, hereinafter referred to as a bridge zone, adjacent these ports so that leakage past either gasket into the bridge zone will not lead to mixing of the media unless the other gasket has also failed. It is normal practice to vent the bridge zone to maintain it at atmospheric pressure and to provide a leakage path for liquid which may leak into it. The normal venting is achieved by providing a localised height reduction or gap in the gasket. This has been known for many years, e.g. from United Kingdom Pat. Specification No. 428,634.

In recent years, there has been a consistent tendency to raise the operating pressures and also the sizes of plates employed, and at the same time the attempt is always being made to reduce the thickness of metal used in the plates, not only to save costly metal, such as stainless steel or titanium, but also to improve the heat transfer therethrough. The increase in operating pressure makes it essential that the venting passage be larger to ensure adequate venting in the event of sudden leakage of high pressure medium into the bridge zone. Also, it increases the tendency of the elastomeric gasket material to migrate into the venting gap, thereby effectively reducing the efficiency of the venting. Further, an increase in the width of the venting gap, or a decrease in the thickness of the metal of the plate, means that there is an increased tendency for metal of an adjacent plate, left unsupported by the venting gap, to buckle under the operating pressure in the adjacent flow space and cause leakage from that flow space.

According to the present invention the gasket for a heat exchanger plate is formed, in the region of the vent gaps, of a harder material than in the sealing regions whereby extrusion into the vent gaps is prevented.

The harder regions may be integral with the main part of the gasket or they may be separate inserts adapted to be'permanently or semi-permanently sealed to the plates.

The invention further consists in a heat exchange plate having a gasket according to the invention as set forth above and in a plate heat exchanger comprising a pack of plates having gaskets according to the invention as set forth above.

FIG. I is an elevated view of part of a gasket accord,

ing to a preferred form of the invention;

FIG. 2 is a section on the lines B-B of FIG. I. showing one plate groove with a gasket and a second one without;

FIG. 3 is a section similar to that of FIG. 2, on the line CC of FIG. 1; and

FIG. 4 is a section on the line AA of FIG. 1, showing portions of 3 consecutive plates with the gaskets.

FIG. 1 shows a corner portion of a gasket 3 surrounding a port P and a bridge zone B which has to be vented via a pair of gaps 2. In order to prevent extrusion of the gasket material into the gaps 2, the zones 1 on either side thereof are formed of material harder than the main body of the gasket.

FIG. 2 shows a plate 6 with its gasket 3 which normally engages under pressure with a second plate 7.

The gasket 3 is shown in the as manufactured form. It is normal for the shape of the gasket and the elastomeric properties of the material of construction to be chosen so that on tightening the plates to an operable condition the gasket shape is altered whereby the sealing face which co-operates with the adjacent plate becomes aligned on a plane X-X to provide a sealing force. Material I adjacent to and across the leakage gap 2, although integral with and part of the seal as manufactured is considerably harder and therefore resistant to distortion which would arise from the application of heat or pressure. Consequently the desired gap 2, FIG. 4, in the gasket is maintained throughout its working life. Unlike the main body ofthe gasket whose material and shape is specifically designed for a chosen degree of distortion the material I is desired to resist deformation. and the cross sectional dimensions are preferably reduced just to fill the seal groove as shown in FIG. 3 to provide support for the adjacent seal 4 on either side, FIG. 4, these being required to resist hydraulic pressure.

On occasion, the gasket is subdivided into a main moulding and two port ring mouldings which when assembled abut in the vicinity of the port/bridge. Any or all three could include the harder material in the region of the leakage grooves.

In the case, where there is a positive gap, the connecting link 5 across the gap might well be omitted and this would simplify moulding.

Various other modifications may be made within the scope of the invention. Thus the harder zones need not be integral with the main body of the gasket, but could be abutted thereto in the gap adjacent the vented spaces.

I claim:

1. A sealing arrangement for a heat exchanger plate having port apertures, a flow space zone and bridge zones between selected port apertures and the flow space zone, the bridge zones being isolated in use by the sealing arrangement from other respective port apertures and the flow space zone and being vented, the sealing arrangement comprising a peripheral gasket portion surrounding the flow space zone, a gasket portion surrounding each port aperture isolated from the flow space zone, and linking gasket portions between the peripheral gasket portion and the port aperture gasket portions, the said linkage portions having vent gaps and being formed, in the region of the said vent gaps,

of a material harder than the material used for the sealing gasket portions whereby extrusion into the vent gaps is prevented.

2. A sealing arrangement as claimed in claim 1. in which the harder regions are integral with the main part of the gasket.

3. A sealing arrangement as claimed in claim 2. in which the portions of the harder regions which are in tended to contact the adjacent plate are of reduced dimension in comparison with the sealing portions.

4. A heat exchanger plate having port apertures. a How space zone and bridge zones between selected port apertures and the flow space zone. the bridge zones being isolated in use by the sealing arrangement from other respective port apertures and the flow space zone being vented. and a sealing arrangement comprising a peripheral gasket portion surrounding the flow space zone, a gasket portion surrounding each port aperture isolated from the flow space zone. and linking gasket portions between the peripheral gasket portion and the port aperture gasket portions, the linkage portions having vent gaps and being formed, in the region of the said vent gaps. of a material harder than the material used for the sealing gasket portions whereby extrusion into the vent gaps is prevented.

5. A heat exchanger plate as claimed in claim 4, in which the harder regions are integral with the main part of the gasket.

6. A heat exchanger plate as claimed in claim 5, in which the portions of the harder regions which are intended to contact the adjacent plate are of reduced dimension in comparison with the sealing portions.

7. A plate heat exchanger comprising a pack of plates in spaced facc-to-face arrangement. each plate having port apertures. a flow space zone and bridge zones between selected port apertures and the flow space zone. the bridge zones being isolated in use by the sealing ar rangement from other respective port apertures and the flow space zone and being vented. and a sealing arrangement comprising a peripheral gasket portion surrounding the ilow space zone. a gasket portion surrounding each port aperture isolated from the flow space zone. and linking gasket portions between the peripheral gasket portion and the port aperture gasket portions. the said leakage portions having vent gaps and being formed. in the region of the said vent gaps, of a material used for the sealing gasket portions whereby extrusion into the vent gaps is prevented.

8. A plate heat exchanger as claimed in claim 7, in which the harder regions are integral with the main part of the gasket.

9. A plate heat exchanger as claimed in claim 8, in which the portions of the harder regions which are intended to contact the adjacent plate are of reduced dimension in comparison with the sealing portions. 

1. A sealing arrangement for a heat exchanger plate having port apertures, a flow space zone and bridge zones between selected port apertures and the flow space zone, the bridge zones being isolated in use by the sealing arrangement from other respective port apertures and the flow space zone and being vented, the sealing arrangement comprising a peripheral gasket portion surrounding the flow space zone, a gasket portion surrounding each port aperture isolated from the flow space zone, and linking gasket portions between the peripheral gasket portion and the port aperture gasket portions, the said linkage portions having vent gaps and being formed, in the region of the said vent gaps, of a material harder than the material used for the sealing gasket portions whereby extrusion into the vent gaps is prevented.
 2. A sealing arrangement as claimed in claim 1, in which the harder regions are integral with the main part of the gasket.
 3. A sealing arrangement as claimed in claim 2, in which the portions of the harder regions whiCh are intended to contact the adjacent plate are of reduced dimension in comparison with the sealing portions.
 4. A heat exchanger plate having port apertures, a flow space zone and bridge zones between selected port apertures and the flow space zone, the bridge zones being isolated in use by the sealing arrangement from other respective port apertures and the flow space zone being vented, and a sealing arrangement comprising a peripheral gasket portion surrounding the flow space zone, a gasket portion surrounding each port aperture isolated from the flow space zone, and linking gasket portions between the peripheral gasket portion and the port aperture gasket portions, the linkage portions having vent gaps and being formed, in the region of the said vent gaps, of a material harder than the material used for the sealing gasket portions whereby extrusion into the vent gaps is prevented.
 5. A heat exchanger plate as claimed in claim 4, in which the harder regions are integral with the main part of the gasket.
 6. A heat exchanger plate as claimed in claim 5, in which the portions of the harder regions which are intended to contact the adjacent plate are of reduced dimension in comparison with the sealing portions.
 7. A plate heat exchanger comprising a pack of plates in spaced face-to-face arrangement, each plate having port apertures, a flow space zone and bridge zones between selected port apertures and the flow space zone, the bridge zones being isolated in use by the sealing arrangement from other respective port apertures and the flow space zone and being vented, and a sealing arrangement comprising a peripheral gasket portion surrounding the flow space zone, a gasket portion surrounding each port aperture isolated from the flow space zone, and linking gasket portions between the peripheral gasket portion and the port aperture gasket portions, the said leakage portions having vent gaps and being formed, in the region of the said vent gaps, of a material used for the sealing gasket portions whereby extrusion into the vent gaps is prevented.
 8. A plate heat exchanger as claimed in claim 7, in which the harder regions are integral with the main part of the gasket.
 9. A plate heat exchanger as claimed in claim 8, in which the portions of the harder regions which are intended to contact the adjacent plate are of reduced dimension in comparison with the sealing portions. 